1. Field of the Invention
The invention relates generally to the field of programmable heating, ventilation, and air conditioning (HVAC) systems. More particularly, the invention relates to energy saving programmable HVAC systems. Specifically, a preferred implementation of the invention relates to recovering from a lost personal identification number situation and restoring programmability to a device usable in conjunction with a usage monitoring programmable HVAC system.
2. Discussion of the Related Art
Heating, ventilation, and air conditioning (HVAC) systems consume a large amount of energy. Commonly, heating and cooling operations are controlled automatically with a thermostat or plurality of thermostats which initiate these operations according to preset temperature limits. The thermostat can be located at a predetermined central local or the plurality of thermostats can be located at a predetermined plurality of locations. The thermostats are capable of detecting changes in room temperature. When the room temperature fluctuates outside the preset high and low temperature limits, the thermostats can trigger a heating, ventilation, and air conditioning unit to heat or cool the room, thus maintaining the room temperature between the preset limits. The thermostats regulate room temperature in this manner regardless of whether or not the building is occupied. Since many buildings may be unoccupied for certain periods of time, the continuous operation of such conventional HVAC systems would result in wastage of a large amount of energy. Attempts have been made to reduce energy wastage by including a timer that simply terminates HVAC system function during a preset interval. Such provision is often impractical since most buildings do not have regular occupancy patterns.
Another problem associated with conventional HVAC systems is the unavailability of personalized billing. Generally, all users of a conventional HVAC system have to pay an equal portion of fixed and variable costs associated with continued operations of the HVAC system. As a result, users often have to pay for HVAC services used by another user.
Heretofore, the requirements of energy conservation and personalized billing referred to above have not been fully met. What is needed is a solution that simultaneously addresses both of these requirements.